How to Identify and Repair Rotting Wood | Ask This Old House

In this video, Ask This Old House general contractor Tom Silva takes host Kevin O'Connor through the causes of wood rot, how to avoid it, and what to do when it occurs.
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Host Kevin O'Connor and general contractor Tom Silva discuss identifying wood rot and what to do about it. After discussing some of the key ways to keep wood from rotting, like flashing and avoiding ground contact, the two discuss the signs of wood rot.
Prevention is Key
For the most part, rotting wood is preventable, but it requires keeping water away from the house as much as possible. This means installing gutters and maintaining them, preventing the wood from coming in contact with the ground, and properly flashing any openings that water could sneak into. Also, seal any outdoor wood surfaces like fascia, window sills, and trim with a sealer or primer-don't forget the backs!
Signs of Rot
It's important to know what to look for when identifying wood rot.
First, look for peeling paint on wood surfaces. This indicates that water is penetrating the wood. As the sun dries the board, it pulls the water through the wood and separates the paint from the surface.
Also, look for soft, punky wood that flakes off. This is advanced rot and can be a sign of carpenter ants.
Replace or Repair?
If you can replace the rotting wood easily, you should. This could be the case for window and door trim, fascia boards, decking, and other wood that's easily accessible and readily available. Just be sure to seal and flash the board so the rot doesn't come back.
But, replacing a board isn't always easy. In the case of window or door sills, replacing the rotted wood can be a big job-one that's not necessary if enough good wood still exists. In that case, it's better to remove as much of the rotten, compromised wood as possible by scraping, cutting, or sanding before repairing.
Fixing Rotten Wood in Place
Once the rotten wood is removed, you can repair it in place with products explicitly meant for the job. A rotted wood restorer can be applied to the damaged wood to restore its strength before repairing it. You can then apply a high-quality wood filler to the surface with a putty knife. Most of these wood fillers are two-part formulas, and it's a good idea to go light on the hardener, not heavy.
When the filler dries, sand it to a smooth, even finish to hide repair before priming and painting.
Where to find it?
Tom recommends preventing rot from happening in the first place by ensuring windows and doors are flashed properly, gutters are hung correctly, and water is being diverted away from the building. If a small amount of rot is detected, it's possible to repair it to keep it from spreading. In the segment, Tom used a combination of wood filler [amzn.to/3pS8yvS] and wood rot restorer [amzn.to/3JEbeFp] manufactured by Bondo, a 3M product [www.3m.com/3M/en_US/bondo-us/].
Tom's other tools and materials to demonstrate repairing rot, including the putty knife [amzn.to/3zmxQFM] and a palm sander [amzn.to/3sSKH1a], can be found at home centers.
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From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. Ask This Old House helps you protect and preserve your greatest investment-your home.
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How to Identify and Repair Rotting Wood | Ask This Old House
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[@Mike__B]

I love how he opens the can and his first instinct is to sniff it "... there's a lot of solvents in it..."

[@jeffthewhiff]

I just completed a project for a customer where it was necessary to remove quite a lot of rotted wood from under several window sills and the epoxy wood filler did a great job. Incidentally, I replaced the old wood trim with PVC, so it will never rot. Good video!

[@MojoPup]

Thanks for another great video guys! I first used that stuff to rebuild a door jamb in a 100 year old prairie house. Worked great, lasted the 12 years I was there.

[@psergiu]

Finally, you guys started putting up link for the products used in the description ! It was always annoying seeing "this new and improved magical thing" that was exactly what you needed but you had to freeze frame and zoom in to guess what it is.

[@gloriouslyimperfect]

You can always go to the website.

[@dtemp132]

Yes, more of this please TOH

[@Katwoman4318]

🤣😅😂🤣👏

[@obscuriosities]

Yes, they even (seemingly deliberately) turn the labels away & don’t refer to the product. Maybe be when making the vids they’re trying to get sponsorship or something? I honestly stopped bothering to watch this channels vids bc of this.

[@Restoration2024]

@@obscuriosities Just as in movies & TV, the program's producers would have to obtain permission from the manufacturer in order to display the label. Also, in showing the label, they would essentially be providing free advertisement to the company. Since this is created for public TV and relies on paying sponsors, it doesn't make sense for them to give away a promotion like that.

[@ALAPINO]

Always makes me smile a little seeing Kevin's Momentum watch.

[@salvadorsepulveda6415]

Thanks for the lesson !! Blessings

[@lasinmt106]

Great advice and discussion on how to approach and use these wood repair products. I bought a 22 year old RV in Feb in Bend OR. Probably sold below freezing to hide the rotting mildew smell. OH boy once we warmed up it got worse & worse. Thought I'd fixed it when just at the end of that fix I discovered another source in another part of the RV. First was in the floor under the fresh water tank. Knew how to prevent the problem in the future. BUT the next one was in the wall. I'm in the throes of fixing the wall as we speak which goes into the edge of floor meet wall too. I finished scraping all black and dark spots out along with rotting wood today. Removed a vinyl wall paper that was probably part of the wall product to begin with not applied after the wall was installed. Clearly the window above this wall area was the source of the leak. So of course that's on the agenda to fix asap but first the wall and I've put in place strong plastic cover and duct tape to prevent leakage while I repair the wall. So my only complaint to date including this video ... is they are all vertical repairs or tutorials and I have to work about a 30 x 60" area across the wall where the dinette and bench seats are placed. I've removed all the wall paper and the strange wood underneath is super thin layers pressed together probably with some wood type of glue and some layers came with the wall paper vinyl when stripped off. Any that was dry and still stuck well and smooth I left. My plan is to treat the entire area where the vinyl is removed with a form of wood hardener. I'm in a steep learning curve having never owned an RV in my life and I'm in my 70's. So yes it is crystal clear the seller knew about the problem. Even added hard flooring to hide some of it. I've removed those boards and actually scraped away all the bad areas and hit with three of my favorite moldicide products. Make that 4 I found another one I like. I'm not a fan of perfumed products. My favorite is Oxine not activated and made into a strong dilution. Also Moldex with out bleach formula, and Odorban lemon and lemon lysol along with Microban all purpose cleaner that seems to do an amazing job on foam and fabric mildew scented products but also this punky wood. And the ply wood that provides the seat for the bench cushions also had picked up the scent and sure enough the Microban 24 hour bacteria killing Multi Purpose Fresh Scent spray has done wonders over all my other products even the stronger dilutions. But I tend to use all over a few days drying each time well. Then I wipe clean with alcohol 71-89% bought at the store since sometimes these products can leave a residue that might effect painting or wood filler etc. from doing it's job. My plan now is to run a strong fan on the wall 24 hours for about 3-4 days. Making sure it's definitely dried out. Treat with wood hardener. With no experience I play to see what 4 layers looks like up to 6 even 7 if need be. Then I also have the wood filler like you demonstrated probably same brand but does have the hardner. And cover the entire area plus right over the areas that wall paper still clings as it would not release without damage to the wall so I need a smooth sanded surface when done. I intend to apply a heavy duty self adhesive vinyl wall cover over the entire area under the window right over original bits I could not remove and smooth it out. Then add trim probably a wood trim strip to hide the seams where the old vinyl paper ends and the new begins. Color scheme should match well enough. I'm not looking for a high end job just one that comes out decent and fools the eye or the casual eye thinking everything looks good. I don't intend to sell this unit I got myself into this mess and I searched 2 years for this RV without landing one so I'm hanging in there with it. However it was neglected all her life and in that neglect itself it was abused. But low miles and good engine and bones she just needs some TLC and updated technology and deep deep deep cleaning inside and out. So far she's got a new bath faucet, shower head, toilet, sky light, dome vent fan, also added new TV antenna and fancy MaxxAir fan that replaced the original just 14x14" vent in the coach. The new fan moves air both ways at 10 settings.I've got it set to exhaust at 40% speed all day and night with the large fan running to dry out the wood wall now. As of yesterday through today I smell zero mildew. No signs of trouble like this anywhere else. My husband installed the back up camera today which works really well and new tow mirrors as the originals were frozen and couldn't be adjusted. My hopes it would be road ready by next weekend is more like with luck by end of July. I'm upholstering the dinette, fabric trim and sofa because though photos showed a clean looking RV it was far from it. Instead of shampooing and living with it knowing the dirt was really still there I had to remove and replace foam etc. too. Far more work than ever I had in mind. The windows are my most difficult challenge. I did identify the main glaze rubbers in their two sizes for the three windows but there's a damaged area for rubber on the horizontal T that I can not ID and it rarely is replaced but because there's 4-5 inches damaged I suspect we need to. U;n watching all the videos on using both wood hardeners and fillers as I can. So far all are for wood that's horizontal not a wall or vertical. We are expected heavy rains over the next 3 days so I'm waiting to apply the wood hardener until our humidity goes down. But I'd love to take advantage of our cooler temps as a low weather cycle moves through. July in NW MT can bring very high temps with it's drier weather.

[@Mr.Pop0]

I swear to god bondo is my fav tool. Ive repaired so many doors that were rotting out at the bottom using the wood restore and bondo.

[@azianchick3529]

Thank you so much for this video!! I have a shed and part of the wood looks like it is rotting. Just a small section so I feel confident I can save it after watching this video. I want to get into the trades so bad but I feel so inadequate and not "handy" enough. But maybe after doing small projects like this, I'll gain more knowledge and confidence.

[@LIOTBs]

I Love this Old House you guys are amazing!

[@bengoolie5197]

Tom is THE MAN!

[@brocktonma.1816]

He’s using all purpose bondo. Works amazing dries fast. If the hole is deep do it in stages.

[@rosemaryr.long-morgan9704]

Hi Thanks for posting these videos. I have wood rot in decorative trim (it has 2 indented strips along the length of trim) that runs the length of bathtub insert, vertically. It looks like the previous tenant just painted over the issue in past and now there's a hole - after removing calking that needed a redo. Is there a bonding product I need to use before using wood rot epoxy & which would You recommend for bathroom application. (Ontario) Thanks

[@Guardducks]

I have mixed up bondo in high heat and it never made it to the wood, it set that fast.

[@campeau29]

After 12 years of use, I have stained french doors getting some rot on the lower rails. Thinking of chiseling out the rot and using bondo, but it's not going to stain well. So thinking of making the bondo patch and then adding an outer matching stained board at the bottom to take the weather. Good or bad idea?

[@christophergoc7543]

I’m in dental school and when we mix a putty to make a mold of the teeth we are taught to measure the same way- make a little circle of the base and run a bead of activator across it. Really cool to see that technique applied here!

[@jonq8714]

You use wood filler for teeth? George Washington would be proud.

[@theloneviking9145]

Same for body filler when doing bodywork on a car

[@christiannavarro9396]

@@theloneviking9145wow that’s interesting this method is in many different careers I wouldn’t expect

[@theloneviking9145]

@@christiannavarro9396 being sort of a guy who likes to fix and make things, I’m amazed how many disciplines carryover to others. For example, when skim coating sheet rock or feather edging a plaster repair, it’s very much like putting on body filler and there’s a whole other bunch examples, I can’t think of right now, but you’ll discover this if you haven’t already

[@StoneE4]

Most hosts advise viewers to use respiratory protection when using volatile chemicals. Kevin just huffs it. 🤣

[@donc-m4900]

He didn't seem to flinch. 😂

[@borys444]

He does double shots of goof off when he’s not working so huffing a little restorer is nothing.

[@Mr.Pop0]

Health concerns? The opioid crisis says hi.

[@saulgoodman2018]

He only opened it for 2 seconds. We all take a sniff of something when we open it.

[@Guardducks]

@@donc-m4900 and that wood conditioner is nasty stuff. It will rot your brain.

[@ericmathis5511]

I have an issue with rott in the main structional support beam 4×6 beam with a 2×6 on top and a 2×12 under the beam with cement blocks under that. How can I replace the rotted area without replacing the whole beam under the wall?

[@jonq8714]

Can you use this on a deck skirting that's moist? I pulled some deck boards and the moisture has rotted a bunch of the wood (I butted the deck boards together expecting shrinkage and the shrinkage never happened so it stayed moist from no air flow...).

[@johnroberts9560]

HI TOH , that's a sweet dollhouse Tommy , I know a lot of little girls would love too have one like that !!! 😊🛠

[@Opus766]

Kevin huffing solvent 3:02

[@thayalansuntharalingam1051]

What about load bearing parts?

[@vazz22]

I Love this channel

[@xy_w1350]

Great work

[@rebeccaramirez-]

Interesting...

[@user-oc4np2bu2r]

What are the names of the products used?

[@gregboshell977]

Tommy my house is built on a 4+6 and the floor doesn't go all the way and the wall joist set on top of the rough cut wood what kind of build is that called my house has younger and

[@mrswolls]

how hard is replacing the sill is doing this a better idea?

[@beach0045]

I just did one; will to a milling store to get a sill that matched; that cost me $30; cutting it to fit the opening, cutting out the old molding, fitting, then caulking, was a right PITA; I have a matching one that's not quite as badly decayed; just got Minwax hardener and Wood Filler, have scraped away the punky wood, I hope well enough; waiting for it to stop raining and dry out to do this thing. Having read more comments since I ordered, I suspect regular old Bondo would also have done this, probably cheaper; but--hope to know in a week.

[@jamesedwards1528]

Hey Tommy we got winds to fix here if your looking to make a show

[@pklemm1]

Tommy! Nice running into you today at Home Depot.

[@langer24106]

You mean the “home center”

[@aurvaroy6670]

You're either one lucky guy/gal or a typical troll on KZbin

[@pklemm1]

@@aurvaroy6670 haha it happened I was caught off guard. Just told him I was a big fan.

[@charlyrodzz]

Wood swells when humid, does that product cracks when wood expands?

[@michaelgreer8659]

I've always wondered what was wrong with wood when it's soft and spongy.

[@henrywhh]

What brand of hardener and filler?

[@jackmahoney3687]

Bondo

[@donaldlewis2360]

You have to respect the integrity of Tommy and Kevin. The only two guys on the internet who actually wear thier wedding rings.

[@lasinmt106]

Really I've seen many men wear theirs. I grew up in a railroad family and the men in the 50's often choose as my Dad did not to wear a ring on the job. My dads uncle died in the 30's when wearing a ring it was welded to his hand when working on an automobile and he lost his finger but infection before penicillin and other antibiotics were available he got infection that went into his blood stream. Anyway I'm a female who's been married 51 years to my husband and in my 70's. We met caving and climbing and I often choose not to wear any rings in my single days because I knew the dangers that my dad and grandfather also on the NP taught me. One day I put the ring on for a job interview. I got home later and my husband asked me to help him with something on the back end of the pickup. I jumped off when done and my hand with the ring caught on the camper bed's shell as I hit the ground I quickly scrambled back up and yanked the ring off asap. My finger popped as I pulled the ring off in the nick of time. I had discovered the first year we were married I was allergic to the gold ring and if I wore it for more than a few hours it caused my finger's skin to peel away and burn and itch really bad. Anyone who knows me even just meeting me for the first time will realize within minutes no doubt I"M married. And no one messes with me or about me. A ring means NOTHING as not one but several men I've known over the years strayed during their marriages and when my husband was present when two of these men were picking up girls when out of town for work one lady said but you are married and he said SO What...and off they went. So I think it's great they wear their rings but they are not THE ONLY ONES. A ring means nothing or it can mean everything but to me a ring means personal choices and not always a statement to the world to be viewed positive or negatively. I respected my Dad and Mom's choice together for him not to wear one as they both agreed with his line of work. And my husband and my friends are fine with me not wearing a ring. I have never pierced my ears either because I have been allergic to other metals since I was a little girl. But I thought I could wear gold only to find out I can't. I'm allergic to latex too so no to those rubber rings some people are wearing. My husband of 51 years choose not to wear a ring too and hey no one has ever called him on it. A few strangers have remarked on me not wearing one. That's called discrimination and it's always men btw that have objected. My guy now in his 80's is fine.

[@sarahcobetto5613]

Shocking i did not know they were married to each other!

[@Bremend]

Anyone recognize the container right away from the bondo chronicles?

[@Nill757]

What about temperature expansion difference between the original wood and the filler? Is it going to crack and split away in a couple years.

[@TobiasRaphael1]

I've used this for this type of application. I live where there is extreme temperature differences with dry and then very humid, very cold and very hot too. Years after the repair, they did not crack with these extremes.

[@Nill757]

@@TobiasRaphael1 Thanks. I wonder if the same is true for Bondo, the car body repair material.

[@TobiasRaphael1]

@@Nill757 I suspect it is the car bondo repackaged as wood filler. It smells like it and has the same characteristics.

[@0822angela]

How do I know who to trust to fix rotting wood UNDER my windowsill without getting ripped off? It’s on the second floor.

[@l.crossjr]

Can paint caulk do the trick?

[@grizzlygrizzle]

No. Simply no.

[@johnroberts2444]

All i heard was flashing & doll house ,what's going on at that doll house ?!!! 😂😂😂

[@saadzeb8055]

Wood filler chemical name ?

[@mrpiccolo23]

I can't believe Kevin sniffed the epoxy product!

[@zach9081]

I have a corner of a porch post that has rotted away. Can anyone recommend a product like this that is thicker so that I can dig out the rot and fix it? It could be 2-3 inches deep and this product looks too runny.

[@alexanderdrakh5237]

You can also consider something like DAPPlastic Wood-X. But whether you use the Bondo hardener mentioned above or the Wood-X, I think you need to use the wood rot restorer first

[@borys444]

Use jb weld kwik wood, it’s much better then that bondo garbage.

[@augustreil]

You might be able to build a little form like they do with concrete ? I had to do the same thing with a rotten sill and used tape as a form.

[@sternmg]

You could try a partial replacement, as shown at this TOH video: kzbin.info/www/bejne/qWfRkpR6d9eNicU "How to repair a rotted porch post". Don't forget to diagnose and fix the root cause. - Rot on structural elements is not something to only address with a gooey fill.

[@augustreil]

@@sternmg, I forgot, ''Tractor Time with Tim'' had a guy come to his garage and drive steel down right next to the post edges. It looked like it worked perfect. Here's the link: kzbin.info/www/bejne/r2infGeNfNCXaac

[@shericreates]

I have a HUGE problem. I have a loan through our City. Not a Grant, a loan!! I had to use their contractors. Last January, in WA State they roofed my home but didn’t cover my roof in downpours after removing shingles. First contractors got fired and second came in who also didn’t cover my roof before shingles. AND the facia boards are half the size the original ones were so all my rafter tails are wet and rotten. Inside the house water was running down my walls and shorting out my light switches. It’s a big mess and I feel like walking away. I need a new house. The City and contractors walked away and won’t even finish their work. In the mist of lawyers but who wants to take on two contractors and a City. What a mess!

[@Mr.Pop0]

Let your house go to mold town USA, then sue their panties off.

[@grizzlygrizzle]

Stick with the private sector. Independent contractors have to have some kind of reputation, which you can find out. If things go bad, you can sue them. And never get unnecessarily entangled with a government infested with Democrats. The Republicans aren't much better, but Democrats are reliably corrupt.

[@PEACHPIG]

💪🏻

[@dachicagoan8185]

They cut the video before he could react to being ridiculed with the doll house lol

[@nathanlamberson1256]

Hey tommy, i am in the process of building a dollhouse, WITH all the correct framing from scratch. if you wanna check it out let me know by replying back here.

[@syahtech1616]

So scary

[@josephrhodes2896]

This video literally makes no sense. This isn’t “repairing / restoring rotted wood” this is just filling in holes. Wood rots from the edges mostly. Once that wood is gone there’s nothing you can do. Filling in the center of that wood did nothing to save the rest of it. Both looks and strength are now compromised. Remove the wood and replace , otherwise what’s the point of this? It’s not going to bring back the rotted edges, it’s not going to allow you to re-add what you broke off...

[@sherriianiro747]

I agree. I had the same problem and was going to use this but did a little digging and there was mold way down under the sill and window had tiny leak at the top, so mold would have been sealed inside creating health hazard. I ended up replacing the entire window.

[@NIGHTMARE-zy7tq]

Bondo and Resin....

[@stalker42]

Anyone else staring at the nails pointed upward near where they were putting their hands?

[@Mr.Pop0]

That wood filler is too expensive and small, buy the 1-gallon general-purpose filler instead.

[@neptune4167]

Uh, dont sniff the chemicals lol.

[@tomobedlam9045]

I'd just replace the wood.

[@martymcfly5842]

Take out rotting wood and replace it with maintenance free PVC. Problem solved.

[@saulgoodman2018]

And why did Kevin go and smell it?

[@dudehenchman]

Not sure what brand he is using there, but the minwax wood filler is STINKY!

[@BradleyAllenNewman]

And now, boys and girls, this is where we break out a little something called BONDO.

[@elpotrodeloyola]

Isnt easier ,cheaper and faster to just replace the board?

[@ThisNamesNowTaken]

2:08 is a biiiii…. I thought he was going to talk the way many of us do

[@TheRonnierate]

?

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